This invention relates to a percussion fuse particularly useful with training ammunition such as mortar and howitzer training projectiles.
In fuse design it is necessary that the fuse function on the particular item of ammunition only at the time and under the circumstances desired, which for a mortar shell is at the time of impact with a desired target. Consequently, the fuse must be safe during handling, transportation, loading, and immediately after firing until the projectile has travelled a safe distance from the launching tube. In addition it is highly desirable that the fuse have an arming indicator which can be seen in the assembled round to shown clearly whether the fuse is safe or armed.
In the past fuses of various designs and safety mechanisms have be proposed. Typical prior designs are shown in U.S. Pat. Nos. 4,006,690; 3,995,556; 3,726,230; 3,375,786; 3,151,558; 2,870,713; 2,845,866; 2,359,752; 2,243,621; and 1,944,780. Prior training ammunition projectiles and fuses are also discussed in U.S. Army Training Manual TM9-1315-249-12 4 P, Chapter 1. However, none of these are satisfactory in cost and operation, particularly when applied to practice ammunition shells.
Accordingly, the primary object of this invention is to provide a novel, relatively simple, inexpensive detonating fuse assembly particularly useful with artillery training ammunition such as mortar shells which satisfies the safety requirements itemized above.
Another object resides in the provision of a novel fuse assembly comprising a slidable striker pin which upon impact with a target will detonate a composition signal charge. A safety system is incorporated within the fuse assembly and includes a slide pin which in the safe condition prevents contact of the striker pin with the signal charge, a set back pin which holds the slide pin in its safe position, and a manually removable pull pin which holds the set back pin in position. During handling and transportation these elements prevent detonation of the shell. Upon loading a shell in a launch tube, the pull pin is removed but the set back pin remains in safe position until after the shell is launched and is retracted only after a required inertial set back force, e.g. 700"G", is attained. The slider pin is then moved to an armed position out of the path of the striker. The safety system further includes a delay feature formed by a plurality of gravity responsive stop balls which in a safe position prevent the striker from contacting the charge during the initial upward flight of the projectile. Only after the projectile reaches its terminal velocity and begins its downward flight do the balls move under gravity to an armed position to fully arm the fuse at a safe distance from the launch tube as the shell approaches its target.
Still another object of the invention resides in the provision of a novel, totally integrated, self contained fuse assembly affording the above safety features and comprising a body, a striker unit slidably mounted within the body, a signal charge readily removably mounted within the body, and a detonating safety and delay system mounted within the body and permitting the fuse assembly to become fully armed only after predetermined in-flight conditions have been satisfied. Signal exhaust ports are provided in the body and, upon detonation of the charge, release signal, flash, and smoke report immediately at the nose end of the practice shell.
Yet another object of the invention resides in the provision of the above self-contained fuse assembly which may be made totally inert simply by removing from the body the signal charge which may be a standard shotgun shell loaded with a pyrotechnic that upon target impact will discharge a signal consisting of a loud report, a large volume of smoke, and a distinguishable flash.
Another object of the invention resides in the provision of the novel self-contained fuse assembly described above which is simple and low cost in manufacture, thus making it particularly useful for practice ammunition such as mortar shells. The assembly may be used with mortars fixed with various propelling charges and will properly function without any field adjustment for range, rotation, pressure, velocity, geology, temperature, or environment.
Still other objects and advantages of the invention will become apparent from reading the following detailed description of the invention wherein reference is made to the accompanying drawing in which like numerals indicate like elements.